Engine cylinder mounting



I 2, 1940- H. HlRTH 7 2,185,848

ENGINE CYLINDER MOUNTING Filed June 22-, 1937 fiyMKAL/J;

Patented Jan. 2, 19 40 p 2,185,8 'l f ENGINE CYLINDER MOUNTING. HellinuthHirth, StuttgarflGei-many, assignor to Hirth Mo toren Q. m. b. .11.; Stuttgart Zuffenhausen, Germany Application June 22, rest-serial No. 1l9, 640

In Germany June 23,1936

1 '3 claims. (01. 121-494) 7 lldyinvention relates' to piston engines driven by a suitable driving fiuid and, quite particularly to internal combustion engines. It deals more particularly with the means'for fixing the cylinder headronthe cylinder. -f 1 .It' is an object of my invention to provide an arrangement'inwhich the cylinder of such engines andm'ore' especially'the air-cooled heads of the cylindersof light weight engines, which are "made lu as 'a" rule from light metals and, more especially in heated condition, possess a comparatively low' mechanical strength, can be fixed on the cylinders in a particularly simple and efficient man ner.

15 Hitherto the head was fixed as a rule to the cylinder bymeans of a few, for instance four,

strong screw bolts and nuts which pulled the head down onto the cylinder. In this, arrangef ment the heads were subject to distortion, which 20 frequently resulted in leakage between the head and the cylinder. The valve seats leaked in some places and eventually even the head would break. Any distortions of the heads would under certain circumstances also influence the cylinder 25 proper, causing the innersliding surface of the" cylinder to get out of true or become wavy and damaging the piston.

My invention has for one of its purposes to" where they are secured by a means permitting 40 the bolts to be tensioned.

I'prefer curving that part of the strap, which embraces thecylinder head, according to a continuous curve, for instance a half-circle or halfellipse. Twosuch straps used for fixing the head 45 to the cylinder and crank case may cross each other in the center of the cylinder head or may extend around the head in parallel.

' In this arrangement the forces transmitted by the screw bolts, which hitherto acted on several 50 individual points, are distributed over larger surfaces. Apart therefrom the peculiar shape of the screw bolts, which are curved hairpin fashion,

is utilized for exerting on the head concentric pressure which counteracts the tensional forces resulting from the bending stresses.

- g of example.

' 'Inthe drawing afilxed to this specification and I I formingfpart thereof two'embodimentsjof myfin Vention are illustrated diagrammatically'by way" Fig. l is' a front Televation, 'partly in section, of v one embodiment,

Fig. 2, beinga'jplan View, p'a'rtly insection; ig. 3 is a'fron't elevation, partly in'se'ction, of 'thejsec'olnd' embodiment and;

' Fig34' is a plan view of Fig. 3.

Fig. 5 is a section illustrating a detail on a larger scale.

In both embodiments shown in'the drawing l is the cylinder head, 2 is the cylinder, 3 isa wall of thecrank case, to which the cylinder is fixed, (tare stay bolts connecting the three parts with {each other, these bolts being curved into U- shaped strap form, the curved portions 5 embracing the cylinder head l,while the free ends ex-v I tending downwardly parallel to-the cylinder axis and through thecrank case wall and enlarged at 1 and formed here with screw thread or with ahead, a nut such as 8 in Fig. 3, or a cap screw,-

a clamp or the like serving to exert tensional forceon the straps.

In the embodiment of the Figs. 1 and 2 the curved middle portions 5 of the strap-shaped bolts 4 cross one another, and the part 5 is heresupported throughout its length by a suitable seat formed on the cylinder head in such manner that no bending stresses can arise, but mere tensional stresses. The bolts 4 enter and leave the cylinder head I in tangential direction (Figs; 1 and 3)- and therefore do not exert any bending force on these points of the head. The curvature of the bolts and of the surfaces supporting same should be a continuous one, either according to a half circle or a half-ellipse.

When screwing up the bolts 4, the curved part 40 5 exerts pressure in radial direction on its support and thus compresses the material at the very places at which otherwise, tensional strains would arise, so that here the material is considerably relieved.

If in View ofauxillary dev ces mounted on the cylinder head i itappears impossible or undesirable to arrange the bolts withthe curved parts 5 crossing each othenas shown in Fig. 2, the bolts 4 may also be arranged with the curved parts5 extending in parallel, as shown in Figs. 3 and 4, where they hold the cylinder vhead together in one direction, while in the direction at right angles thereto the head is stiffened sufficiently by the auxiliarydevices; v

with the air-cooled cylinder heads for light en,-

gines, which are provided with cooling ribs 9. As shown more particularly in Fig. 3, the head is 15 here provided also with cooling ribs I 1 'of a peculiar configuration, which are curved in the direction of the curved parts 5 of the bolts, whereby their cooling effect is enhanced, since curved ribs possess a larger cooling surface than plane ribs.

20 Apart therefrom the curved ribs II have a superior stiffening efiect on the cylinder I. I prefer shaping these ribs according to concentric circles about .a point on the middle line of the cylinder 2.

25 The new mode of fixation of the cylinder heads can however also be used with advantage in connection with water-cooled cylinder'heads, and its application is not confined to internal combustion engines.

n In the drawing the bolts 4, 5 are shown as having a cylindrical cross section, which will obother.

viously be the most favorable form. However bolts of difierent cross sections, for instance elliptical or rectangular, might be used as well.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a personskilled in the art.

i I claim:

1. In an engine in combination, a crank case,

-a cylinder mounted on and supported by said crank case, a cylinder head on said cylinder provided with a seating portion, a U-shaped screw bolt having a curved portion embracing said seating portion and downwardly depending leg portions extending through the wall of and into said crank case and nuts on the ends of said screw boltarranged to press said head down on said cylinder and said cylinder on said crank case.

2. The combination of claim 1, in which the cylinder head is providedwith seats on the opposite sides of said head and two U-bolts extend in parallel around the cylinder head in contact with said seats and into contact withthe. crank case.

3. The combinationof claim 1, in which two U-shaped screw bolts extend around the cylinder head embracing the seating portions of the cylinder head with their curved parts crossing each 7 I-IELLMUTH HTRTH. 

